Recently, the ZYS113G fully computerized three-boom rock drilling jumbo developed by CRCHI has achieved remarkable results in tunnel excavation profiling and overbreak/underbreak control at a plateau railway tunnel. In terms of smooth blasting performance, the blast hole residual trace rate exceeds 90%, and the blast hole utilization rate is around 95%. Regarding overbreak and underbreak, the average linear overbreak in Grade IV surrounding rock is 17–19 cm, and in Grade III surrounding rock it is 13–14 cm. In terms of unit consumption of blasting materials, the unit consumption for double-track hard rock tunnels has been reduced from about 1.3 kg/m³ to 1.05–1.1 kg/m³; for single-track hard rock and soft rock tunnels, it has been reduced from 1.3–1.5 kg/m³ to about 1.1 kg/m³.

On-site construction with CRCHI's fully computerized three-boom rock drilling jumbo

The CRCHI ZYS113G fully computerized three-boom rock drilling jumbo features automatic precise positioning and efficient precision drilling. After design parameters are entered into the jumbo's computer, the machine identifies known points on the tunnel arch and wall via a 3D scanner and calculates its position relative to the tunnel. Through precise positioning of the jumbo and import and calculation of design parameters (alignment, excavation profile, blasting design, etc.), the central control platform displays information such as the depth, position, and angle of specific blast holes, and the operator can complete precise drilling by operating the joystick according to the computer display.

Tunnel cross-section

To effectively control tunnel overbreak and underbreak, the client proposed precise low-vibration shaped-charge blasting technology. "Precise" requires the rock drilling jumbo to drill accurately, achieving "accurate" hole positions (position deviation no greater than 3 cm), "even" hole bottoms (hole bottoms should lie in the same cross-section with deviation no greater than 10 cm), "uniform" perimeter holes (even spacing with spacing deviation no greater than 5 cm), and "parallel" holes (blast holes parallel, with intersection angle preferably no greater than 2° and parallel to the alignment centerline). The CRCHI ZYS113G fully computerized three-boom rock drilling jumbo achieved accuracy, evenness, uniformity, and parallelism on site, contributing to the client's improvement of tunnel excavation quality.